1. Field of the Invention
This invention relates to a well-boring apparatus for drilling of subterranean formations for the recovery of fossil fuel deposits in the form of gas, oil and other liquified products. More particularly, this invention relates to an apparatus for drilling oil and gas wells comprising a hybrid drill bit, which provides both a cutting function and a separate heating function. The cutting function is provided by conventional cutting elements while the heating function is provided by a laser source that projects at least one laser beam ahead of the drill bit during the well-boring process to soften and/or melt materials, such as rock formations, disposed in the drilling path. This invention also relates to a well-boring apparatus comprising a drill bit assembly comprising at least one of a chromatographic analysis system and a laser spectroscopy assembly, whereby analysis of materials (e.g. rocks and vapors) disposed in the vicinity of the drill bit during operation of the drilling apparatus is enabled.
2. Description of Related Art
It is well known that substantial, heretofore untapped reserves of fossil fuels, including oil and natural gas, are buried deep within the ground. Access to these reserves may be obtained by means of well-bores that are produced by drilling apparatuses, which generally employ drill bits having hard and durable cutting contact elements. However, frequently these reserves are disposed beneath hard geological formations, e.g. rocks, which may even be impenetrable using conventional drilling equipment. Drilling of such hard formations requires a substantial amount of time and generally results in high costs. In addition, the drill bits used to drill through these hard formations are subject to extensive wear and/or damage. Impenetrable formations require the use of overly complex drilling routes in order to circumvent the formations and, in some cases, may result in complete abandonment of the drilling operation.
In addition to hard geological formations, unstable formations, e.g. shale, are frequently encountered, which formations may cause damage to and/or loss of drilling equipment. Unstable formations may also cause entrapment and subsequent abandonment of the drilling equipment.
One solution to the problems associated with the use of conventional drilling equipment, which as previously stated employ drill bits comprising one or more mechanical cutting elements, has been to use laser beams as a means of boring wells into the earth. For example, U.S. Pat. No. 4,066,138 to Salisbury et al. teaches an earth boring apparatus mounted above ground that directs an annulus of high powered laser energy downwardly for boring a cylindrical hole by fusing successive annular regions of the stratum to be penetrated at a power level that shatters and self-ejects successive cores from the hole. U.S. Pat. No. 4,113,036 to Stout teaches a laser drilling method and system of fossil fuel recovery in which a vertical bore hole is drilled into an underground formation, a laser beam is projected through the vertical borehole and reflected horizontally from the hole through the formation along a matrix of bores. U.S. Pat. No. 3,871,485 to Keenan, Jr. teaches a method of drilling using a laser beam in which a laser beam generator that is electrically connected to an inhole voltage generator actuated by drilling mud or other liquid passing through a laser beam housing connected to the drill string is positioned in the wellhole and a reflecting crystal is positioned within the laser beam housing to reflect the beam in an elliptical pattern across the formation to be penetrated. U.S. Pat. No. 4,090,572 to Welch teaches a method and apparatus for laser treatment of geological formations in which a laser beam is projected into a well bore along a beam guide so as to provide sufficient laser energy to melt or vaporize the formations under down-hole conditions. Similarly, U.S. Pat. No. 5,107,936 to Foppe teaches a heat drilling process employing laser beams as a heat source in which the profile of the borehole is melted down by the heat source and the resulting molten rock is pressed into the surrounding side rock during the drilling process such that only a gap defining the outer profile of the borehole is melted down, which surrounds a drill core, which is extracted at an adjustable distance behind the melting zone.
Numerous techniques exist for monitoring wellbores during the production and completion of wellbores, monitoring reservoir conditions, estimating quantities of hydrocarbons, operating downhole devices in wellbores, and determining the physical condition of the wellbore and downhole devices. Sensors disposed in the wellbore, such as temperature sensors, pressure sensors, accelerometers and hydrophones have been used to obtain continuous wellbore and formation information.
Conventional drilling of wells relies upon the use of a drilling fluid to recover shards of drilled rock and remove them from the well-bore, typically by bringing them up to the surface. These shards can then be filtered out of the mixture and analyzed to determine the type and properties of the rock formation being drilled. However, when lasers are used to perform drilling, the materials being drilled are vaporized, as a result of which there remain no shards of rock for analysis. It is, however, still important to be able to assess the conditions local to the drilling site.